Observations of soft X-ray spectrum from a Seyfert 1 and a narrow emission-line galaxy

Abstract

We report X-ray spectral observations of the Seyfert 1 galaxy Mrk 509 and the narrow emission-line galaxy, NGC 2992. Spectral analysis of the simultaneously obtained 0.2-4.0 keV pulse height data is presented. The absorbing column density N_H, in the line of sight to Mrk 509 is found to be consistent with no absorption intrinsic to the source. A two-component spectrum in Mrk 509 is required, under the assumption that the galactic obscuration is at least that measured ona large scale by 21 cm line surveys. The soft spectral component in Mrk 509 is interpreted as thermal emission from a hot gas. The X-ray spectrum of NGC 2992 is well described by a single-component power law with photon index, Γ=1.78 and N_H=4×10²¹ cm⁻². The N_H obtained in line of sight is less than the value predicted from the reddening of Balmer lines but comparable to that predicted from the nonstellar optical continuum. A partial covering by "patchy" absorbers is indicated for NGC 2992. The covered fraction seems to be variable over a time scale of a few years.